First, clean the tooth using the tap water and toothbrush only. Then, I put 雙氧水 in a small cup and soak the tooth into 雙氧水 for 3 days. Finally, use tap water to wash the tooth to remove 雙氧水 and then dry the tooth. The tooth should be dried totally. You can use hair dryer. I keep the tooth for more then 1 year. Still white and clean, no decay.